1. Field of the Invention
The present invention relates to a recording tape cartridge which accommodates, within a case, a single reel on which is wound a recording tape, such as a magnetic tape or the like, which is used as a recording/playback medium mainly of computers or the like.
2. Description of the Related Art
Them have conventionally been known recording tape cartridges in which a recording tape, such as a magnetic tape or the like which is used as a data recording/playback medium (for data backup) of computers or the like, is wound on a reel, and the reel is singly and rotatably accommodated within a case which is made of a synthetic resin. Such a recording tape cartridge is generally structured such that at the time when the recording tape cartridge is not in use (is not loaded in a drive device) the reel is mechanically braked in the rotating direction, and, in the rotation axis direction, is merely urged by an urging means such as a compression coil spring or the like.
However, here, if an impact is applied to the recording tape cartridge due to the recording tape cartridge being handled by a user or being dropped or the like when the recording tape cartridge is not in use, due to this impact, the reel easily moves in the rotation axis direction, and, depending on the case, there is the problem that the rotating direction braking of the reel is cancelled and wrinkles or the like are formed in the recording tape. Therefore, in recent years, recording tape cartridges have been proposed which are structured such that, when not in use, the reel is restricted so as to not move in the rotation axis direction, and, when in use, this restriction is released simply, such as disclosed in Japanese Patent Application Laid-Open (JP-A) No. 2005-276416 for example.
The above-described recording tape cartridge is structured such that, when the recording tape cartridge is not in use, locking members enter-in between an upper flange of the reel and a ceiling plate of the case, and the reel is thereby restricted so as to not move in the rotation axis direction. Namely, the leeway for the reel to move in the rotation axis direction is eliminated by the locking members. When the recording tape cartridge is being used, a releasing operation, in which a braking member which restricts the reel so as to not move in the rotating direction is raised-up by a releasing member of the drive devices is utilized such that a taper portion formed at the locking members is pushed, and the locking members are thereby slid in a radial direction of the reel and withdrawn (the restriction of the locking members is released).
In order to ensure space for movement of the locking members in the radial direction of the reel due to the braking member moving in the rotation axis direction of the reel, the angle of the taper portion formed at the locking member is made to be 45°. However, if the taper portion of the locking members is 45°, the component of force of the force applied in the rotation axis direction of the reel works greatly, and therefore, rubbing arises between the locking members and the inner surface of the ceiling plate of the case, and there is the problem that the powder-like substance generated at the time of this rubbing increases the sliding resistance (the dynamic friction coefficient) of the locking members with respect to the inner surface of the ceiling plate of the case.
When the sliding resistance (the dynamic friction coefficient) of the locking members with respect to the inner surface of the ceiling plate of the case increases, a very large moving force (lock releasing force) in the rotation axis direction of the reel is needed at the braking member. Therefore, overload is applied to the driving source which lowers the recording tape cartridge relative to a reference plane of the drive device, and trouble or the like is brought about at the drive device. Further, there are cases in which tight-winding deformation arises at the hub of the reel due to the recording tape being wound onto the hub. In such cases, there is the problem that the flanges which are welded to the hub deform in directions of approaching the recording tape.